Expansible bracelet



June 7, '1949. A. PRETRE EXPANSIBLE BRACELET Filed Jan. 3l, 1948 Patented June 7, 1949 UNITED STATES PATENT OFFICE EXPANSIBLE BRACELET Armand Pretre, Geneva, Switzerland, assignor to Montres Rolex SA (Rolex Watch Co. Ltd.), a corporation of Switzerland Application January 31, 1948, Serial No. 5,642L

in Switzerland February 5, 1947 Claims. i

This invention relates to an expansible bracelet or like device comprising a plurality of units each of which is hingedly connected with a link member slidable in the next adjacent unit, and a spring being housed within each unit, between a part thereof and a part of the link which is hingedly connected with the preceding unit.

It is an object of the invention to provide new and improved means for allowing expansion and effecting the contraction of the device in order that the spring action be more perfect than has heretofore been done.

According to an important feature of the invention the spring is in the shape of a coil spring the axis of which is arcuate and Which bears by its extremities on the unit, while the link of the preceding adjacent unit is attached to the median portion of the said spring and tends to deform it centripetally in the direction of its chord when expanding the bracelet.

Fig. 1 is a perspective view of a unit substantially in the shape of a hollow parallelepiped having two elongated side apertures, one of which is for the passage of the link of the adjacent unit and the other aperture is for the passage of its own link to which it is hingedly connected.

Fig. 2 is a perspective view of a link member to which is attached the corresponding spring member in the shape of a coil spring.

Fig. 3 is a perspective view of a bar intended as an abutment for limiting the expansion movement of the bracelet.

Fig. 4 is a perspective view of a hinge member formed of two trunnions held axially spaced apart by a spring and intended to hingedly connect a unit with its slide link.

Fig. 5 is a fragmentary sectional top view showing a pluarilty of units partially expanded.

The middle unit I of the Fig. 5 is in the shape of a hollow parallelipiped as shown in Fig. 1 and is provided with two opposite elongated side apertures 1 and 1. The unit I is connected to the adjacent unit 2 by a link 3 as shown in perspective in Fig. 2. This link 3 is hingedly connected to the unit I by means of two trunnions 4 shown in perspective in Fig. 4 and held apart from each other by a coil spring 5.

In assembling the bracelet the hinge member constituted by the two trunnions 4 and the spring 5 may be inserted into the cylindrical curved end 6 of the U-shaped link 3. The spring 5 being compressed, the link member may then be inserted into the unit I through the elongated side aperture 1 thereof. When released within the unit I, the trunnions 4 take the position shown in Fig. 5 under the action of the spring 5, in which position the trunnions hingedly connect the slide link 3 to the unit I.

The link 3 of the unit I may be assembled in the same manner by means of the spring loaded trunnions 5'. Now the link 3' may be connected to the unit i in the following manner:

A coil spring 8 is attached to the link 3 in the same manner as the spring 8 is attached to the link 3 of Fig. 2. If the end portions of this spring are bent backwards between the upper and lower arms of the U-shaped link, the springcarrying end of the link 3 may be easily introduced into the unit I within which the spring Il will then tend to expand and take the arcuate position shown in Fig. 5 thus holding the link 3' in assembled position within the unit I.

It is to be understood that the bracelet or like device may be constituted by a plurality of link and unit assemblies such as that hereinbefore described and without further securing means.

However in order to limit the expansion of the bracelet, it will be convenient to insert into each unit a bar 9 shown in Fig. 3 which will be placed in the free space between the upper and lower arms of the U-shaped link.

The bar 9 may be easily introduced into the unit by pushing it obliquely through the aperture l. When the bar 5 is fully introduced in the unit I the spring 8 repeals and holds it into the position shown in Fig. 5.

The expansion of the bracelet is performed against the pressure of the spring 8' owing to the fact that this spring which is normally arcuate becomes centripetally deformed in the direction of the chord of its arc which direction corresponds to the direction of the traction exerted on the link to which the spring is attached. The yaxis of the coil spring 8 will occupy at; the end of the expansion a position represented by the dash-and-dot line 8" of Fig. 5.

However this expansion will be limited by the bar 9 which prevents the link from getting out of the unit owing -to the middle portion of the spring running against the said bar.

The units and the links may be stamped from sheet metal so that the cost of manufacturing the bracelet is reduced; assembling of the bracelet is also simplied as `it will 4be seen from Ithe foregoing s-pecication.

The box-like units are strong 'and rigid.

It will be noticed that the manner in which the coil springs are deformed at the very moment Where the expansion causes them to pass' from 1a maximum to a minimum tractive eiort, that is to say through a kind of tensile drop as far as they come near to the expanded position 8, with the result that a comparatively strong tension about the wrist is secured, thus preventing any untimely expansion while a cornparatively weak tension is provided at the time of maximum expansion when the bracelet is to be expanded to its full size to allow the hand to be passed therethrough.

Inversely, in the known constructions of eX- pansible bracelets, the springs reach their maximum tension when the hand is to be `passed through the bracelet and they are then released when the bracelet rests upon the wrist.

What I claim is:

l. In an expansible bracelet or the like, in combination a plurality of connected units, each unit comprising a box-like outer member and an inner link hingedly connected therewith and slidably mounted in fthe outer member of the next adjacent unit, an arcuate coil spring housed within the box-like outer member of each unit, said arcuate coil spring bearing by its extremities against said outer member :and being attached by its median portion to the link of the preceding adjacent unit, whereby expansion of the bracelet causes said` arcuate coil spring to be centripetally deformed in the direction of its chord.

2. In an expansible bracelet or the like, the combination as claimed in claim 1, wherein the slide link is a U-shaped plate.

3. In an expansible bracelet or the like, `the combination as claimed in claim 1, wherein the slide link is a U-shaped plate the closed end of which forms a tube at each extremity of which a trunnion is sl-idably mounted, :a coil spring being housed within said tubular portion of the link and tending to urge said trunnions apart from one another.

4. In an expansible bracelet or the like, the combination as claimed in claim 1, wherein the slide link is a U-shaped plate between the arms of which extends transversely a bar resting on the inner wall of the outer member of each unit to limit the expansion of the bracelet.

5. In :an expansible bracelet or the like, the combination as claimed in claim l, wherein the slide link is a U-shaped plate between the arms of which extends transversely -a bar resting on the inner wall of the outer member of each unit to limit the expansion of the bracelet, the coil spring resting by its both extremities against said transverse bar.

ARMAND PRETRE.

No references cited. 

